From e03265003096038a3990ef140f56a320dc9fad12 Mon Sep 17 00:00:00 2001
From: fnicon <mybeddrom@gmail.com>
Date: Sat, 21 Mar 2026 23:38:34 +0900
Subject: [PATCH] add force sum

---
 game/love_src/src/system/racing_force.lua | 151 ++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 game/love_src/src/system/racing_force.lua

diff --git a/game/love_src/src/system/racing_force.lua b/game/love_src/src/system/racing_force.lua
new file mode 100644
index 0000000..959f244
--- /dev/null
+++ b/game/love_src/src/system/racing_force.lua
@@ -0,0 +1,151 @@
+local vm = require("lib.vornmath")
+
+
+---calculate real desire forward after weight
+---@param forward number gas_input
+---@param weight number? magic weight constant
+---@return number forward actual desire
+local function add_forward(forward, weight)
+  return forward * (weight or 1.0)
+end
+
+---calculate real desire lateral steer after weight
+---@param steer number steer_input
+---@param weight number? magic weight constant
+---@return number lateral
+local function add_lateral(steer, weight)
+  return steer * (weight or 1.0)
+end
+
+---calculate friction impact based on grip
+---@param friction number outside friction
+---@param grip number car's grip
+---@return number friction
+local function grip_force(friction, grip)
+  return friction * grip
+end
+
+---add friction
+---@param f vec2 vec2 input
+---@param grip number car's grip
+---@param friction number floor's friction
+---@param weight_tire number? magic weight tire
+---@param weight_floor number? magic weight floor
+---@return vec2 f vec2 output
+local function add_friction(f, grip, friction, weight_tire, weight_floor)
+  local f_grip = grip_force(grip, friction)
+  -- tire - floor
+  return f + f_grip * ((weight_tire or 1.0) - (weight_floor or 0.0))
+end
+
+---calculate drag's impact based on streamline
+---@param drag number|vec2 drag
+---@param streamline number car's streamline
+---@return number drag
+local function drag_force(drag, streamline)
+  return streamline * drag
+end
+
+---add drag into f
+---@param f vec2 input
+---@param drag number|vec2 drag
+---@param streamline number car's streamline
+---@param weight_drag_boost number? magic weight
+---@param weight_drag_halt number? magic weight
+---@return vec2 f
+local function add_drag(v, drag, streamline, weight_drag_boost, weight_drag_halt)
+  local f_drag = drag_force(drag, streamline)
+  return v + f_drag * ((weight_drag_boost or 1.0) - (weight_drag_halt or 0.0))
+end
+
+---add inertia into f
+---@param f vec2 input
+---@param inertia_force vec2 inertia
+---@param inertia_weight number? magic weight
+---@return vec2 f
+local function add_inertia(f, inertia_force, inertia_weight)
+  return f + inertia_force * (inertia_weight or 1.0)
+end
+
+---centrifugal_force
+---@param mass number car's mass
+---@param angular_v number velocity on angular
+---@param perpendicular number r
+---@return number f
+local function centrifugal_force(mass, angular_v, perpendicular)
+  return mass * angular_v ^ 2 * perpendicular
+end
+
+---add centrifugal
+---@param f vec2
+---@param mass number
+---@param inertia_force vec2
+---@param weight_centrifugal number?
+---@return vec2 f
+local function add_centrifugal(v, mass, inertia_force, weight_centrifugal)
+  local centrifugal = centrifugal_force(mass, inertia_force[1], inertia_force[2])
+
+  local new_v
+  if (v[2] > 0) then
+    new_v = v - vm.vec2(0.0, 1.0) * centrifugal * (weight_centrifugal or 1.0)
+  elseif (v[2] < 0) then
+    new_v = v + vm.vec2(0.0, 1.0) * centrifugal  * (weight_centrifugal or 1.0)
+  end
+  return new_v
+end
+
+---create desire f
+---@param desire_forward number forward
+---@param desire_steer number lateral
+---@param weight_forward number? weight forward
+---@param weight_steer number? weight lateral
+---@return vec2 desire f
+local function add_desire(desire_forward, desire_steer, weight_forward, weight_steer)
+  local forward = add_forward(desire_forward)
+  local lateral = add_lateral(desire_steer)
+  local val = vm.vec2(forward, lateral)
+  return val
+end
+
+---@param desire_forward number engine's force
+---@param desire_steer number axle's steer
+---@param grip number car's grip
+---@param friction number outside's friction
+---@param drag number|vec2 outside's drag
+---@param streamline number car's streamline
+---@param inertia_force vec2 last's force
+---@param mass number car's mass
+---@param weight_forward number? magic weight
+---@param weight_steer number? magic weight
+---@param weight_tire number? magic weight
+---@param weight_floor number? magic weight
+---@param weight_drag_boost number? magic weight
+---@param weight_drag_halt number? magic weight
+---@param weight_inertia number? magic weight
+---@param weight_centrifugal number? magic weight
+local function force_workflow(
+  desire_forward, desire_steer,
+  -- friction
+  grip, friction,
+  -- drag
+  drag, streamline,
+  -- inertia
+  inertia_force,
+  -- centrifugal
+  mass,
+  weight_forward, weight_steer,
+  weight_tire, weight_floor,
+  weight_drag_boost, weight_drag_halt,
+  weight_inertia,
+  weight_centrifugal
+)
+  local val = add_desire(desire_forward, desire_steer, weight_forward, weight_steer)
+  val = add_friction(val, grip, friction, weight_tire, weight_floor)
+  val = add_drag(val, drag, streamline, weight_drag_boost, weight_drag_halt)
+  val = add_inertia(val, inertia_force, weight_inertia)
+  val = add_centrifugal(val, mass, inertia_force, weight_centrifugal)
+
+  return val
+end
+
+return force_workflow